### Abstract

Peculiar velocity surveys present a very promising route to measuring the growth rate of large-scale structure and its scale dependence. However, individual peculiar velocity surveys suffer from large statistical errors due to the intrinsic scatter in the relations used to infer a galaxy's true distance. In this context, we use a Fisher matrix formalism to investigate the statistical benefits of combining multiple peculiar velocity surveys. We find that for all cases we consider that there is a marked improvement on constraints on the linear growth rate f sigma(8). For example, the constraining power of only a few peculiar velocity measurements is such that the addition of the 2MASS Tully-Fisher survey (containing only similar to 2000 galaxies) to the full redshift and peculiar velocity samples of the 6-degree Field Galaxy Survey (containing similar to 110 000 redshifts and similar to 9000 velocities) can improve growth rate constraints by similar to 20 per cent. Furthermore, the combination of the future TAIPAN and WALLABY+ WNSHS surveys has the potential to reach a similar to 3 per cent error on f sigma(8), which will place tight limits on possible extensions to General Relativity. We then turn to look at potential systematics in growth rate measurements that can arise due to incorrect calibration of the peculiar velocity zero-point and from scale-dependent spatial and velocity bias. For next-generation surveys, we find that neglecting velocity bias in particular has the potential to bias constraints on the growth rate by over 5 sigma, but that an offset in the zero-point has negligible impact on the velocity power spectrum.

Original language | English |
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Pages (from-to) | 2517-2544 |

Number of pages | 28 |

Journal | Monthly Notices of the Royal Astronomical Society |

Volume | 464 |

Issue number | 3 |

DOIs | |

Publication status | Published - 21 Jan 2017 |

### Cite this

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*Monthly Notices of the Royal Astronomical Society*, vol. 464, no. 3, pp. 2517-2544. https://doi.org/10.1093/mnras/stw2466

**Cosmological forecasts for combined and next-generation peculiar velocity surveys.** / Howlett, Cullan; Staveley-Smith, Lister; Blake, Chris.

Research output: Contribution to journal › Article

TY - JOUR

T1 - Cosmological forecasts for combined and next-generation peculiar velocity surveys

AU - Howlett, Cullan

AU - Staveley-Smith, Lister

AU - Blake, Chris

PY - 2017/1/21

Y1 - 2017/1/21

N2 - Peculiar velocity surveys present a very promising route to measuring the growth rate of large-scale structure and its scale dependence. However, individual peculiar velocity surveys suffer from large statistical errors due to the intrinsic scatter in the relations used to infer a galaxy's true distance. In this context, we use a Fisher matrix formalism to investigate the statistical benefits of combining multiple peculiar velocity surveys. We find that for all cases we consider that there is a marked improvement on constraints on the linear growth rate f sigma(8). For example, the constraining power of only a few peculiar velocity measurements is such that the addition of the 2MASS Tully-Fisher survey (containing only similar to 2000 galaxies) to the full redshift and peculiar velocity samples of the 6-degree Field Galaxy Survey (containing similar to 110 000 redshifts and similar to 9000 velocities) can improve growth rate constraints by similar to 20 per cent. Furthermore, the combination of the future TAIPAN and WALLABY+ WNSHS surveys has the potential to reach a similar to 3 per cent error on f sigma(8), which will place tight limits on possible extensions to General Relativity. We then turn to look at potential systematics in growth rate measurements that can arise due to incorrect calibration of the peculiar velocity zero-point and from scale-dependent spatial and velocity bias. For next-generation surveys, we find that neglecting velocity bias in particular has the potential to bias constraints on the growth rate by over 5 sigma, but that an offset in the zero-point has negligible impact on the velocity power spectrum.

AB - Peculiar velocity surveys present a very promising route to measuring the growth rate of large-scale structure and its scale dependence. However, individual peculiar velocity surveys suffer from large statistical errors due to the intrinsic scatter in the relations used to infer a galaxy's true distance. In this context, we use a Fisher matrix formalism to investigate the statistical benefits of combining multiple peculiar velocity surveys. We find that for all cases we consider that there is a marked improvement on constraints on the linear growth rate f sigma(8). For example, the constraining power of only a few peculiar velocity measurements is such that the addition of the 2MASS Tully-Fisher survey (containing only similar to 2000 galaxies) to the full redshift and peculiar velocity samples of the 6-degree Field Galaxy Survey (containing similar to 110 000 redshifts and similar to 9000 velocities) can improve growth rate constraints by similar to 20 per cent. Furthermore, the combination of the future TAIPAN and WALLABY+ WNSHS surveys has the potential to reach a similar to 3 per cent error on f sigma(8), which will place tight limits on possible extensions to General Relativity. We then turn to look at potential systematics in growth rate measurements that can arise due to incorrect calibration of the peculiar velocity zero-point and from scale-dependent spatial and velocity bias. For next-generation surveys, we find that neglecting velocity bias in particular has the potential to bias constraints on the growth rate by over 5 sigma, but that an offset in the zero-point has negligible impact on the velocity power spectrum.

KW - cosmological parameters

KW - cosmology: theory

KW - large-scale structure of Universe

KW - 6DF GALAXY SURVEY

KW - OSCILLATION SPECTROSCOPIC SURVEY

KW - REDSHIFT-SPACE DISTORTIONS

KW - ALL-SKY SURVEY

KW - PRIMORDIAL NON-GAUSSIANITY

KW - WEAK-LENSING SURVEYS

KW - DARK ENERGY SURVEY

KW - HI MASS FUNCTION

KW - POWER SPECTRUM

KW - GROWTH-RATE

U2 - 10.1093/mnras/stw2466

DO - 10.1093/mnras/stw2466

M3 - Article

VL - 464

SP - 2517

EP - 2544

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 3

ER -